MIL (engine light) on dash when tach fails

[JBCumminatya]

Engine light comes on while driving or stays on at startup. When the light comes on while driving, the tachometer drops to zero then after a while the needle pops up and continues to work. After a "good" trip or two the light may not come on. Any ideas as to whats happening? Maybe a loose wire or sensor? The 2000 DC service manual states that the tachometer is controlled by the PCM. Does the PCM get a reading from the crankshaft position sensor or the camshaft position sensor to operate the tachometer? I have a problem with paying either Dodge or Cummins NW approx. $75. 00 to confirm that the problem is caused by something stupid like a loose connection.

Any help would be appreciated.

 

[Evan A. Beck]

Definately sounds like a bad connection.



Well, if it were a problem wit your instrument cluster itself, you'd get a "Check Gauges" light. So we can rule that one out right away.



First, do the key cycle thing to check for codes...



Sounds like it is pretty intermittent, so you'll want to check the cam sensor and crank sensor connections. Check all that out and report back...

 

[JBCumminatya]

Hi Evan,



I hope I don't sound ignorant but what is "the key cycle thing to check for codes".

At this time I don't have a device to connect to the chrysler computer plug thats under the dash. Is this what you mean by checking for codes?

On the Cummins website, I've seen a Dodge kit that contains various connectors, that would allow me to check error codes. Cost - about $300. 00

If you are aware of another way to check error codes, please let me know. Thanks in advance.



JBCumminatya

 

[Evan A. Beck]

The key cycle trick works on 99 and up Rams. What you do, is cycle it on-off-on-off-on, and then your odometer will display any codes that are set. Of course, you'll need the service manul code list to figure out what the codes mean. Way cheaper than 300 bucks. :-D When you are doing hte cycle thing, you just have to make sure the odometer appears each time. Try it!

 

[Jhillmann]

I just had the exact same problem repaired. The crank position sensor was going bad. On mine when the tack went to zero the was a definate loss of power while accelerating. If I was already up to speed the only symptom was the check engine light and the tack reading zero.

 

[JBCumminatya]

"key cycle thing"

Hey, Evan



Did the key cycle thing. Odometer produced the code P1693. This is what the odometer showed:



" p1693 ", " ----- ", " pdone ". The following diagnostic trouble codes on page 25-16 of '00 DC service manual: 1- P1693(M)// DTC Detected in Companion Module// A fault has been generated in the companion engine control module. 2- P1693(M)// DTC detected in PCM/ECM or DTC detected in ECM// A "Companion DTC" was set in both the ECM and PCM. Do you recommend I unplug the CKP sensor with the key off, then plug it back in??? Waiting for your expertise.



JBCumminatya

 

[Kent Kuykendall]

I was talking to Blue Chip the other day and was a asking about my stumble and they have had several trucks with your symptoms and they said it was fixed by a Crank Position Sensor. Hope this helps.



Wonder if it would fix my stumble problem too?



Does any one know the cost of one of a Crank Position Sensor?



Kent

 

[JBCumminatya]

Had my truck checked out by Cummins NW the other day. They confirmed the DTC is generated by the CKP sensor. Paid 37 bucks + some change for new sensor. I'll report back when I get it installed.

 

[JBCumminatya]

Replaced the CKP sensor this morning. I have my truck back!